T-square securing means



Aug'. 28, 1951 H. A. cHAPlN T-sQUARE SECURING MEANS 2 Sheets-Sheet 1 Filed Sept. l5. 1949 v INVENTOR. Haro/a ./l. 7m/@11n BY %O-A Aug. 28, 1951 H.AA. CHAPIN T-SQUARE SECURING MEANS uw* .ww H.. 2 V R6 `a s o m u W m k mw m qw m ww RMN. m n .wvwk mMh m Filed sept. 15. v1949 Patented Aug. 28, 1951 f. icl

UNITED STATES PATENT `OFFICE Yr.r-sQUARn sEcURiNG MEANS Harold Addison .Chapin,`, San Jose, Calif.

' Application September 15, 1949, Serial No. 115,915

1 This invention relates to Tf-squares, and more particularly, to a T-square which is adapted to be attached to a drawing board or the like for use by draftsmen.

The main object of the invention is to provide a T-squar-e embodying means whereby the same is readily held in place at a desired position, said means being operated by the user of the T-square to release same from the board whereby the same can be moved to various and desired positions.

Another object of the invention is to provide said T-square with a head, a board gripping member, and spring means operable to force the board-engaging member into contact therewith and thereby hold the Tsquare in desired positions.

`Theinvention is illustrated in the accompanying drawings, in which:

Fig. l shows a top plan view of a drafting board and the T-square attached thereto; lFig. 2 i is a view in side elevation showing the T-square attached to the board; A

Fig. 3 is a longitudinal sectional 'View through the center of the T-square.

Fig. 4 is a section on the line 4-4-of Fig. -1

Fig. 5 is a sectional view on the line 5-5 of Fig. 3;

Fig. 6 is a top plan view of a portion of th head of 4the T-square with theknob and sheath removed;

i Fig. 7 is a bottom view adjacent the end of the blade of the T-square showing the board clamping member and its connection to the operating rod; and Y i i Fig. 8 is a section on thelineu-B of Fig; 3;

` Referring specifically to the drawings, in which l like numerals indicate similar parts throughout the various views, a portion of a drafting board is indicated at 6 to which is attached the present invention, which comprises a T-squar-e including a head 1, a blade portion 8, said blade portion comprising at its respective sides plastic straight edges S and Ill, said straight edges being connected as by a web member il, said web being bent to provide U-shaped portions I2 and I3 at its respective sides, said U-shaped portions rigidly gripping the straight edges 9 and I0 of the blade.

The web portion II has attached to its under side, as by welding or the like, a plate I4 which is bent downwardly as at I5 to form a recess between the web and the under surface thereof for a purpose to later be described.

The T-square is further provided with a housing, or sheath portion, I5 bent at its respective sides I'I to form a recess for accommodating a plate I8. The sheath, or housing, I6 has attached thereto a knob I9 as by a screw 20 extending upwardly throughthe housing into the knob.

The plate I, which is `mounted within the housing I5, has attached to its outer end a bar, or head, 2I as by screws 22, said head having ag groove 23 therein, said groove being adapted to receive one end of an operating rod 24, the operating rod extending longitudinally through the arch l5 form-ed by the plate tl and being connected at its other end as by welding or the like at 25 to an angled board-engaging plate 26.

A tension spring 21 has its opposite legs 2t and 29 connected respectively within recesses formed in the head member 2| and the head member 7, whereby a spring tension is always exerted through the operating rod 24fto the board-engag-4 ing plate 26 `to normally hold the same in en` gagement with the far side oi the drafting board.`

The T-square blade and its head are held in place as by a plurality of screws 39, said 'screws extending through the sheath I inta engagement with the head l. The plate I8 has longitudinal recesses, or guideways, 3I and 32, said guideways accommodating screws 353 and further `limiting the inward and outward mov-ement of the plate I8. The blade of the T-square is longitudinally corrugated as at 33 `and 3d, which tends to strengthen the blade and thereby prevent the same from warping. i i i Itlwill be noted that the operating rod 24 terminates short of the end of the blade 8 and' that the under surface of the blade is provid-ed withan arch-shaped guide member 3d to guide' the member 2t when the same is moved by the operation of the rod 24.

It will be further noted that the board 6 is provided at one of its sides with an over-extending lip portion 3S which is adapted to receive the cut-out portion 31 of the head 'I when the same is in tight engagement with the edge of the board to thereby provide a better bearing surface for the slidable head.

In the operation of the device, the T-square is applied to the board at any desired position, and as will be seen, due to the tension of the spring 2l between the head ZI and the head l, the operating rod 24 being attached to the board engaging angle member 26 normally tends to operate such board engaging angle member and thereby holds the T-square in a tight lit along the edge oi' the board, and thus the user of the T-square is free to use both hands during the drafting op- 1 3 eration as he does not have to hold the T-square against the board.

When it is desired to move the T-square along the board, the operator grips the knob I9 between the thumb and forefinger of the left hand, whereupon he can manipulate the rod 24 through the head 2| as by the remaining lingers of his left hand to thereby compress the spring, move the operating rod 24 inwardly and thus release the clamping plate 26, whereupon the T-square can be readily moved to a new desired position. Then upon releasing of the head 2|, the spring will move the head to the left, thereby moving the operating rod 24 and in consequence the clamping plate 26 against the far edge of the board to again lock the T-square in the new desired position.

It will readily be seen that this is a neat construction, all of the operating parts being substantially concealed and below the surface of the T-square and its arm, and, further, that the same can be readily and easily manipulated for moving the T-square when desired.

The draftsman usingthe device has both hands free for using his instruments, and, further, it eliminates the possibility of the T-square being accidentally moved with the result that inked lines are never accidentally blurred by the slip,- ping of the T-square.

The invention is not intended to be limited to the exact construction shown, the disclosure being a preferred construction of the invention, the same being capable of various modifications within the scope of the following claims.

I claim:

1. A T-square having ahead and a blade, said blade being corrugated longitudinally and provided at opposite sides with straight edges, an upstanding operating knob and a channelshaped housing rigidly attached to the T-sduare head, an operating plate slidable in said housing, an oprating head attached to the underside of said slidable plate, a rod connected to the operating head ofthe plate and extending longitudinally ofthe blade of the T-square, a board-engaging grip attached to the end ofthe rod adjacent the end of the blade, an arched plate connected to the under side of the T-square blade and enclosing and guiding said rod, a spring interposed between the T-square head and the head attached to the operating plate, said spring normally tending to engage the board-engaging grip with a drawing board to hold the T-square in position there- 2. A T-square having a head and a blade, a knob and a channel-shaped housing rigidly connected to the T-square head, a slidable plate hav-t ing oppositely disposed longitudinally extending recesses formed therein, said plate being movable within the housing, an operating head attached to the underside of said slidable plate, an operating rod connected to the head of the slidable plate and mounted beneath the upper surface of the T-square blade and movable thereunder, a board-engaging grip attached to the far end of the operating rod, a guide for said grip, a spring means interposed between the T-square head and the head carrying the operating rod, said spring normally urging the grip to engagement with a drafting board.

3( A T-square securing device comprising a drawing board and a. T-square, said T-square having a head and a blade, an upstanding operating knob mounted on the T-sduare head, a channel-shaped guide housing connected to the op erating knob, an operating plate slidable in the guide v housing, `a depending operating head mounted at the outer end of the operating plate and laterally spaced with respect to the operating knob, a rod connected to the operating head of the plate and extending longitudinally of the blade of the T-square, the blade having an intermediate flat portion and a plate secured to the intermediate flat portion of the blade and having a medial depression therein, the rod lying in the medial depression beneath the blade portion, and a board-engaging grip attached to the end of the rod adjacent the end of the blade, and a spring having one end attached to the T-square head and the other end attached to the head of the operating plate, said spring normally tending to engage the board-engaging grip with the drawing board to hold the T-square in position thereon.

HAROLD ADDISON Cl-IAPIN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,107,432 Mantz Aug. 18, 1914 1,593,097 Ord July 20, 1926 2,085,304 Farrell June 29, 1937 FOREIGN PATENTS Y Number Country Date 2,029 Great Britain Jan. 26, 1897 21,402 Great Britain Sept. 20, 1909 49,647 Germany Nov. 20, 1889 376,191 Great Britain July7, 1932 596.437 France Apr. 7. 1925 

